MSI Afterburner, SpeedFan, Macs Fan Control, Core Temp, smcFanControl, DriveDx, OMEN Gaming Hub, Activity Monitor, MenuMeters, Systempal, Compact Tray Meter, Arx Control, Data Lifeguard Diagnostic, MenuMeters for El Capitan, Real Temp, Corsair Link, XMeters, MiniUsage, TG Pro, WinAudit, iPulse, Atmonitor, SSD-Z, Easytune, MenuBar Stats, RunCat, CheckMyMac, SSD Fan Control, iStatistica, Fanny, Monity, Sidebar Diagnostics, XRG, Hologram Desktop, BitBar, Nerdtool, xbar, CPU Thermometer, eeectl, FullControl, AMD Overdrive Utility, AMD System Monitor, Superbar, Opsview Monitor Mobile, Remote Buddy, Penteract Taskbar Resource Meter, OS Track, MagicanLite, StatsBar, Stater, remote linux monitor, ZetaWatch, Free Disk Space Monitor, SysMetrix are some alternatives to IStat Menus.